The present invention relates to catheter probes based on the use of a fiber that does not rotate. More specifically, the present invention relates to optical coherence tomography based on the use of an optical fiber that does not rotate, which is enclosed in a catheter portion.
Myocardial infarction or heart attack remains the leading cause of death in our society. Unfortunately, most of us can identify a family member or close friend that has suffered from a myocardial infarction. Until recently many investigators believed that coronary arteries critically blocked with atherosclerotic plaque that subsequently progressed to total occlusion was the primary mechanism for myocardial infarction. Recent evidence from many investigational studies, however, clearly indicates that most infarctions are due to sudden rupture of non-critically stenosed coronary arteries due to sudden plaque rupture. For example, Little et al. (Little, W C, Downes, T R, Applegate, R J. The underlying coronary lesion in myocardial infarction: implications for coronary angiography. Clin Cardiol 1991, 14: 868-874, incorporated by reference herein) observed that approximately 70% of patients suffering from an acute plaque rupture were initiated on plaques that were less than 50% occluded as revealed by previous coronary angiography. This and similar observations have been confirmed by other investigators (Nissen, S. Coronary angiography and intravascular ultrasound. Am J Cardiol 2001, 87 (suppl): 15A-20 A, incorporated by reference herein).
The development of technologies to identify these unstable plaques holds the potential to decrease substantially the incidence of acute coronary syndromes that often lead to premature death. Unfortunately, no methods are currently available to the cardiologist that may be applied to specify which coronary plaques are vulnerable and thus prone to rupture. Although treadmill testing has been used for decades to identify patients at greater cardiovascular risk, this approach does not have the specificity to differentiate between stable and vulnerable plaques that are prone to rupture and frequently result in myocardial infarction. Inasmuch as a great deal of information exists regarding the pathology of unstable plaques (determined at autopsy) technologies based upon identifying the well described pathologic appearance of the vulnerable plaque offers a promising long term strategy to solve this problem.
The unstable plaque was first identified and characterized by pathologists in the early 1980's. Davis and coworkers noted that with the reconstruction of serial histological sections in patients with acute myocardial infarctions associated with death, a rupture or fissuring of athermanous plaque was evident (Davis M J, Thomas A C. Plaque fissuring: the cause of acute myocardial infarction, sudden death, and crescendo angina. Br Heart J 1985; 53: 3 63-37 3, incorporated by reference herein). Ulcerated plaques were further characterized as having a thin fibrous cap, increased macrophages with decreased smooth muscle cells and an increased lipid core when compared to non-ulcerated atherosclerotic plaques in human aortas (Davis M J, Richardson E D, Woolf N. Katz O R, Maim J. Risk of thrombosis in human atherosclerotic plaques: role of extracellular lipid, macrophage, and smooth muscle cell content, incorporated by reference herein). Furthermore, no correlation in size of lipid pool and percent stenosis was observed when imaging by coronary angiography. In fact, most cardiologists agree that unstable plaques progress to more stenotic yet stable plaques through progression via rupture with the formation of a mural thrombus and plaque remodeling, but without complete luminal occlusion (Topol E J, Rabbaic R. Strategies to achieve coronary arterial plaque stabilization. Cardiovasc Res 1999; 41: 402-417, incorporated by reference herein). Neovascularization with intra-plaque hemorrhage may also play a role in this progression from small lesions, i.e., those less than about 50% occluded, to larger significant plaques. Yet, if the unique features of unstable plaque could be recognized by the cardiologist and then stabilized, a dramatic decrease may be realized in both acute myocardial infarction and unstable angina syndromes, and in the sudden progression of coronary artery disease.